IT is British racing's oldest guessing game, and it is about to be played again with all the same gusto and enthusiasm as it has been for the past 40 years - what does Lester ride in the Derby? The ball started bouncing again at Goodwood last Tuesday when Lester Piggott partnered the Richard Hannon-trained Geisway to a thrilling, last-stride victory in the ''last chance'' Derby trial, the Predominate Stakes. Coming from four lengths off the pace with half a mile to travel, Piggott angled Geisway to the outside in the final furlong and then, pouncing late and fast, got up in the shadows of the post to beat Beneficial, the 4-6 favourite, by a short head. It was hard to disagree with the smiling Piggott's verdict when he declared on dismounting: ''I was brilliant wasn't I?'' All the old touch and judgement came into play, as he clearly set out to beat one horse, the strongly-fancied Beneficial, and pulledit off in style. Unfortunately, it had been a different story in the Irish 2,000 Guineas at the Curragh the previous Saturday when Piggott brought Vincent O'Brien's Fatherland with a finishing flourish that failed narrowly to catch Barathea, ridden by Michael Roberts. The critics are hard on Piggott, 57, these days, and they were out in force after seeing him just touched off in the Irish Classic. Nevertheless, Fatherland, a colt by Sadler's Wells, gave the impression that he would get a longer trip, even if Epsom might not be the ideal venue to display his galloping talents. Consequently, Piggott was linked with the O'Brien colt, and even after Geisway's performance there seem very little doubt that Fatherland would be the Derby mount. Then, complications set in. It was reported from O'Brien's headquarters in Tipperary that Fatherland had suffered a slight training setback due to an abscess in his foot and had temporarily been placed on the ''easy'' list. The Ballydoyle communique added that it was hoped Fatherland would not be held up more than a few days. Further reports suggest the colt is making good progress, and a decision regarding a Derby start is expected this weekend. So, will Lester be on Fatherland or Geisway? The maestro knows how to play the Derby guessing game, and with a smile and shrug of the shoulders, he is giving nothing away - although prior to the setback, he had hinted that Fatherland could be his choice. Geisway is owned by the very high-profile Jersey businessman Paul Green, also the part-owner of sidelined chaser Carvill's Hill and the ill-fated Mr Brooks, who gave Piggott such a nasty fall at Gulfstream Park, Florida, at the last Breeders' Cup series. Green has supplemented Geisway for the Derby at a cost of GBP10,000, and readily points out: ''Whether Lester thinks my colt can win or not, Geisway has got to take his chance. I will give Lester 48 hours to make up his mind whether he wants to ride him,I'm not hanging about.'' Clearly, Green has not played the ''What does Lester ride in the Derby?'' game before, otherwise he would realise that this quiz, rather like the 'Question of Sport' television series, runs and runs, right to the wire. Who can ever forget Lester jocking off the great Bill Williamson on the eve of Roberto's Derby? Every year that Lester did not have a Derby mount, tabloid newspapers would instil fear into rival jockeys, asking who would be the next to be replaced by theLong Fellow. Geisway, incidentally, was one of three horses purchased by Green from Tony Budge, who sold up his racing and bloodstock interests last year following the collapse of his construction company. The colt has talent but whether he will stay a strongly-run mile and a half is the worry. Before closing, I would like to make mention of a collector's item in racing, which surfaced at the French 2,000 Guineas meeting at Longchamp last Sunday. The official glossy, colour racecard was withdrawn from circulation soon after the first bundle was opened just before 11 am when the mistake was first discovered. An unfortunate error by the Parisien printers and compilers of the racecard had every owner on the day listed as being a Middle Eastern sheik, or ''Cheik'' as written in French. This made for some hilarious reading, Sheik Jacques Wertheimer, Sheik ZenyaYoshida, Sheik Stavros Niarchos, etc . . . I have heard of fears of Arab domination in the racing world, but surely some poor Frenchman was suffering from an acute case of paranoia.